恶性血液病FLT3基因突变的检测及临床意义

为了探讨FLT3基因及FLT3内部串联重复（ITD）突变与恶性血液病的关系及临床意义,采用PCR结合DNA测序技术分析32例急性髓系白血病（AML）、18例急性淋巴细胞白血病（ALL）、2例急性杂合性白血病（AHL）、12例骨髓增生异常综合征（MDS）、10例慢性粒细胞白血病（CML）、3例非何杰金淋巴瘤（NHL）及9例多发性骨髓瘤（MM）患者骨髓单个核细胞中FLT3基因及FLT3/ITD突变,分析FLT3/ITD阳性患者的临床特征及疗效。结果表明：在32例AML患者中5例FLT3/ITD（15.6%）阳性,其中7例M3中1例、10例M4中1例、10例M5中3例;而在18例ALL、2例AHL、12例MDS和10例CML患者中未检测到FLT3/ITD突变;在3例非何杰金淋巴瘤（NHL）、9例多发性骨髓瘤（MM）患者中亦未检测到FLT3基因。对2例特征性突变进行了测序,其结果显示,ITD位于外显子14,长度为27-63bp,为单纯串联重复,FLT3/ITD序列包括有2个SH2-结合结构域（YEYV与YEYDLK）,其中1例出现氨基酸的替换,其ITD序列及氨基酸的替换均具有独特性,均未改变FLT3阅读框架。临床研究表明,FLT3/ITD阳性AML患者外周血白细胞数高（p〈0.01）,骨髓原始细胞比例高（p〈0.01）,化疗后有低缓解率趋势。结论：FLT3/ITD突变多见于M5患者,为框内突变。FLT3/ITD阳性的AML患者外周血白细胞数高,骨髓原始细胞比例高,伴低缓解率趋势。FLT3/ITD基因突变可作为预测AML预后的一个指标。

Detection of FLT3 Gene Mutation in Hematologic Malignancies and Its Clinical Significance

To study the FLT3 gene expression and its internal tandem duplication in hematologic malignancies and its clinical significance, polymerase chain reaction (PCR) and DNA sequencing were used to detect the FLT3/ITD mutation in blast cells of bone marrow from 86 patients with hematologic malignancies, including 32 cases of acute myeoloid leukemia (AML), 18 cases of acute lymphoblastic leukemia (ALL), 2 cases of acute hybrid leukemia (AHL), 12 cases of myelodysplastic syndromes (MDS), 10 cases of chronic myelogenous leukemia (CML), 3 cases of non-Hodgkin's lymphoma (NHL) and 9 cases of multiple myeloma (MM). The resultes showed that the expression of FLT3/ITD gene could be detected in 5 of 32 (15.6%) AML patients, including 1/7 of M(3), 1/10 of M(4) and 3/10 of M(5). More FLT3 aberrations were found in AML-M(5). No FLT3/ITD was found in 18 cases of ALL, in 2 cases of AHL, in 12 cases of MDS and in 10 cases of CML. No FLT3 was found in 3 cases of NHL and in 9 cases of MM. Sequence analysis in 2 case with abnormal PCR electrophoretic patterns revealed that the ITDs were located within exon 14 from 27 to 63 bp, which was a simple tandem duplication, and did not altered the reading frame. FLT3/ITD was associated with a higher peripheral blood white cell count (p < 0.01), higher percentage of bone marrow blast cells (p < 0.01) and lower complete mission rate. It is concluded that more FLT3/ITD mutation occurs in AML-M(5) patients. Sequence of the mutants is in frame mutation. FLT3/ITD mutation is associated with higher peripheral blood white cell count, higher percentage of bone marrow blast cells and lower complete remission rate, FIT3/IID gene mutation may be used to predict prognosis of patients with AML.